Steel Material, Process of Fabricating Steel Material, and Apparatus of Fabricating Steel Material

• Main Authors: IWANAGA KENGO, UEKI YOSHIHARU, KODAMA JUN-ICHI, WATANABE OSAMU, OKAMURA TSUKASA, HIRAKAMI DAISUKE, ICHIBA MIKIYUKI
• Format: Patent
• Language: English
• Published: 27.01.2011
• Subjects: ALLOYS; CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TREATMENT OF ALLOYS OR NON-FERROUS METALS

According to one aspect of the present invention, there is provided a process of fabricating a steel material by performing a heat treatment to a steel material having high strength, in order to reduce hardness at one part of the steel material to less than hardness at other parts of the steel material, wherein the heat treatment comprises a heating step in which a portion having a certain depth from a surface of the steel material is rapidly heated by induction heating or direct energization heating, and a cooling step in which the steel material, which has been subject to the heating step, is rapidly cooled a predetermined time after the heating step, and a heating temperature in the heating step is Ac1 transforming point or more.